The Tech Babble
The first thing that generally comes to mind when you think "Pearl Izumi" is cycling, and for good reason: together with parent company Shimano, PI covers 85% of the market. To put that in perspective, the current leader in the running footwear business (Brooks) has a market share of 18%. It's a staggering number!

To no surprise, as triathlon took off Pearl Izumi went headfirst into it, creating numerous apparel and cycling shoe options. And options they have: three different product lines for apparel, three distinct options on the cycling shoe front.

However, PI's running shoes have always left something to be desired. My first experience with PI's running product line came in the form of the original SyncroSeek trail shoe. It's a shoe that makes my top 5 list of worst running shoes ever: heavy as a brick, ran a full size and a half small, and had absolutely no arch in it to speak of. It felt like PI had decided to take one of their mountain biking shoes, slapped a midsole and outsole on it, and called it good.

Not a good first impression. Hello, blacklist.

Thankfully, PI learned from these mistakes. The isoTransition still runs a little short on length, but there is an arch on the inside of the shoe, thanks to the OrthoLite insole. OrthoLite was once used by Nike and Saucony, respectively, for their insoles to their running product line.

The overall theme to the PI product line is what they call 1:1. This is, in their terms, trying to make the athlete and gear one and the same; a mating of the two that is completely natural. PI's big technology hallmark, at least for this particular shoe, is their seamless upper. There are no interior seams anywhere on the shoe. Less seams, of course, should mean less blistering, as there are fewer friction points on the interior of the shoe.

Cushioning comes from a midsole constructed solely from PI's proprietary blend of EVA. No gel pods, no Syncro cradles, no nothing extra. This is a "I'll take my meat and potatoes, thank you very much, nothing else" shoe. Don't take that as meaning that it's under-cushioned; it's just that the shoe is extremely reliant on the ability of the foam to handle the task at hand. Midsole stack heights are 19 millimeters in the heel, 10 millimeters in the forefoot, for an offset of 9 millimeters.

Drainage holes are cut through the bottom of the shoe; this has an unintended consequence which we'll get to during the running section. To complete the shoe, there is an integrated bootie tongue and elastic laces. Total weight for the shoe in a men's size 9 is 7.8 ounces; of course, my size 13 boats weigh in slightly heavier.

The Run
Well, congratulations, Pearl Izumi: you're off my blacklist.

Popping these on, the first thing you notice is, much like the K-Swiss Kwicky Blade Light, is what's not there, rather than what is: there's no impinging seams. There's no pressure points. Instead, you have a shoe that hugs around the foot before opening into a wider toebox to promote forefoot splay. It's comfortable in the same way that, say, walking around in a slide sandal is comfortable: there's only one piece really holding onto your foot, and then the rest of your foot may do as it pleases.

The isoTransition is a neutral shoe, which usually would be bad news for this esteemed author. However, there's some natural stability built in here. Some of that comes from the lowered offset and the natural splay of the forefoot (the wider your toes may spread, the larger the "tripod" your foot can become and be naturally stable). But it also comes from a relatively rigid midfoot region. A small bridge exists only on the medial side of the shoe, giving it additional structure here. It's just enough to allow me to run in it without any type of additional support. I think the best corollary might be some of your structured neutral shoes, a la Asics Nimbus: even though it's neutral, there's just a touch of stability available to those who need it.

There's some serious cushioning underfoot, especially for something with only 10 millimeters of cushioning in the forefoot. The foam has some bounce to it; I'm guessing there's a bit more rubber in the blend of EVA that Pearl Izumi engineered. But the energy return does not come at the cost of pure protection from the road. This is, in my opinion, the result of the drainage holes cut underfoot: it allows the shoe a little bit more room to spread out upon impact, dispersing energy away from the foot.

These holes also make the shoe incredibly flexible in the forefoot. This is good for someone like myself, who has an inherent lack of flexibility in my big toe: I have a hard time with shoes that are very stiff in the forefoot and getting them to respond in sync with my foot. This, on the other hand, is very easy to pick up and go.

Varying stride lengths, it seems like this is a shoe that wants a pretty high cadence. Unsurprising, given some of the athlete's that Pearl Izumi has on the roster: Tim DeBoom and Cait Snow both run with very, very high cadences. Quick turnover really makes this shoe come alive with it's mix of cushioning and energy return.

I have yet to test the drainage on the shoe, as I haven't raced in them yet and that's generally the only time you'll see me dumping gallons of water over my head. But I believe it's safe to say that it will be pretty effective, given that there is drainage from heel to toe.

Overall, it's a great riding shoe for those who like a bit more of a responsive feel underfoot, but don't want to be penalized for doing so. It's a nice mix of road feel, isolation, and fit.